In some respects it's Google's model too. They gave away Google Apps free to small businesses for years as they pursued Microsoft's Exchange Server market. At first Google Apps was free for up to 100 users, then 50, then 10. Now they charge $5 per user per month for new plans. Legacy pricing is grandfathered so they didn't really piss anybody off in the process, but it seems pretty clear the strategy was to subsidize the product and accumulate market share.